Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early g...Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones, P. balsamifera x trichocarpa （PBT） and P. maximowiczii x balsamifera （PMB）, one improved family of Norway spruce （Picea glauca （PA）） and one improved family of white spruce （Picea abies （PG）） growing under different spacings in monocultures and mixed plots. The plantations were established in 2003 in Abitibi-Témiscamingue, Quebec, Canada, in a split plot design with spacing as the whole plot factor （1 × 1 m, 3 × 3 m and 5 × 5 m） and mixture treatments as subplot factor （pure： PBT, PMB, PA and PG, and 1：1 mixture PBT：PA, PBT：PG, PMB：PA and PMB：PG）. Results showed a beneficial effect of the hybrid poplar-spruce mixture on diameter growth for hybrid poplar clones, but not for the 5 × 5 m spacing because of the relatively young age of the plantations. Diameter growth of the spruces decreased in mixed plantings in the 1 × 1 m, while their height growth increased, resulting in similar aboveground biomass per tree across treatments. Because of the large size differences between spruces and poplars, aboveground biomass in the mixed plantings was generally less than that in pure poplar plots. Leaf nitrogen concentration for the two spruce families and hybrid poplar clone PMB was greater in mixed plots than in monocultures, while leaf nitrogen concentration of clone PBT was similar among mixture treatments. Because of its faster growth rate and greater soil resources demands, clone PMB was the only one showing an increase in leaf N with increased spacing between trees. Fine roots density was greater for both hybrid poplars than spruces. The vertical distribution of fine roots was insensitive to mixture treatment.展开更多
Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long-range insect attractants, as they are volatile and permeate for...Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long-range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short-range host plant choice by both adult females and larvae of a folivorous forest pest （Choristoneura fumiferana）. We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix （α-pinene, β-pinene, limonene, myrcene） and to white spruce （Picea glauca） epicuticular waxes in closed arenas. Ovipositing females pre- ferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes ＋ monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene-treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax-only discs, but showed no preference between extremely high monoterpene concentrations and wax-only controls. In an insect-free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg-laying females and feeding larvae, and that their effects are synergistic.展开更多
Heavy metals such nickel (Ni) can cause toxicity by 1) displacing essential components in the biomolecules, 2) blocking the functional group of molecules, or 3) modifying enzymes, proteins, the plasma membrane, and me...Heavy metals such nickel (Ni) can cause toxicity by 1) displacing essential components in the biomolecules, 2) blocking the functional group of molecules, or 3) modifying enzymes, proteins, the plasma membrane, and membrane transporters. The main objective of the present study was to investigate the effect of nickel (Ni) on gene expression of nitrate on gene expression with a focus on the genes coding for the high affinity Ni transporter family protein </span><i><span style="font-family:Verdana;">AT</span></i><span style="font-family:Verdana;">2</span><i><span style="font-family:Verdana;">G</span></i><span style="font-family:Verdana;">16800, and natural resistance-associated macrophage protein (</span><i><span style="font-family:Verdana;">NRAMP</span></i><span style="font-family:Verdana;">). Ni toxicity was assessed by treating seedlings with an aqueous solution of nickel nitrate salt [Ni(NO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">] at the concentrations of 150 mg, 800 mg, and 1600 mg of nickel per 1 kg of dry soil. RT-qPCR was used to measure the expression of </span><i><span style="font-family:Verdana;">AT</span></i><span style="font-family:Verdana;">2</span><i><span style="font-family:Verdana;">G</span></i><span style="font-family:Verdana;">16800, and </span><i><span style="font-family:Verdana;">NRAMP</span></i><span style="font-family:Verdana;"> genes in samples treated with nickel nitrates and controls. The results revealed that </span><i><span style="font-family:Verdana;">P.</span></i> </span><i><span style="font-family:Verdana;">glauca</span></i><span style="font-family:""><span style="font-family:Verdana;"> is resistant to Ni based on lack of plant damage at all nickel concentrations. Ni has no effect on the expression of the </span><i><span style="font-family:Verdana;">AT</span></i><span style="font-family:Verdana;">2</span><i><span style="font-family:Ver展开更多
基金funded by Canada Economic Development,Quebec’s Ministry of Natural Resources and Fauna (MRNF)the Natural Sciences and Engineering Research Council of Canada through a Collaborative and Research Development grant to ADthe Program on Energy Research and Development of Natural Resources Canada
文摘Disease prevention, biodiversity, productivity improvement and ecological considerations are all factors that contribute to increasing interest in mixed plantations. The objective of this study was to evaluate early growth and productivity of two hybrid poplar clones, P. balsamifera x trichocarpa （PBT） and P. maximowiczii x balsamifera （PMB）, one improved family of Norway spruce （Picea glauca （PA）） and one improved family of white spruce （Picea abies （PG）） growing under different spacings in monocultures and mixed plots. The plantations were established in 2003 in Abitibi-Témiscamingue, Quebec, Canada, in a split plot design with spacing as the whole plot factor （1 × 1 m, 3 × 3 m and 5 × 5 m） and mixture treatments as subplot factor （pure： PBT, PMB, PA and PG, and 1：1 mixture PBT：PA, PBT：PG, PMB：PA and PMB：PG）. Results showed a beneficial effect of the hybrid poplar-spruce mixture on diameter growth for hybrid poplar clones, but not for the 5 × 5 m spacing because of the relatively young age of the plantations. Diameter growth of the spruces decreased in mixed plantings in the 1 × 1 m, while their height growth increased, resulting in similar aboveground biomass per tree across treatments. Because of the large size differences between spruces and poplars, aboveground biomass in the mixed plantings was generally less than that in pure poplar plots. Leaf nitrogen concentration for the two spruce families and hybrid poplar clone PMB was greater in mixed plots than in monocultures, while leaf nitrogen concentration of clone PBT was similar among mixture treatments. Because of its faster growth rate and greater soil resources demands, clone PMB was the only one showing an increase in leaf N with increased spacing between trees. Fine roots density was greater for both hybrid poplars than spruces. The vertical distribution of fine roots was insensitive to mixture treatment.
文摘Monoterpenes, source of the distinctive odor of conifers, are generally considered plant defensive compounds. However, they are also known to act as long-range insect attractants, as they are volatile and permeate forest airspaces. Moreover, they are lipid soluble and can be absorbed into plant epicuticular waxes. We test their role in short-range host plant choice by both adult females and larvae of a folivorous forest pest （Choristoneura fumiferana）. We conducted laboratory assays testing the responses of Eastern spruce budworm to an artificial monoterpene mix （α-pinene, β-pinene, limonene, myrcene） and to white spruce （Picea glauca） epicuticular waxes in closed arenas. Ovipositing females pre- ferred filter paper discs treated with P. glauca waxes to controls, and preferred the waxes ＋ monoterpenes treatment to waxes alone. However, females showed no preference between the monoterpene-treated disc and the control when presented without waxes. Feeding larvae prefered wax discs to control discs. They also consumed discs treated with realistic monoterpene concentrations and wax preferentially over wax-only discs, but showed no preference between extremely high monoterpene concentrations and wax-only controls. In an insect-free assay, P. glauca epicuticular wax decreased monoterpene volatilization. These results suggest that P. glauca waxes and realistic concentrations of monoterpenes are stimulatory to both egg-laying females and feeding larvae, and that their effects are synergistic.
文摘Heavy metals such nickel (Ni) can cause toxicity by 1) displacing essential components in the biomolecules, 2) blocking the functional group of molecules, or 3) modifying enzymes, proteins, the plasma membrane, and membrane transporters. The main objective of the present study was to investigate the effect of nickel (Ni) on gene expression of nitrate on gene expression with a focus on the genes coding for the high affinity Ni transporter family protein </span><i><span style="font-family:Verdana;">AT</span></i><span style="font-family:Verdana;">2</span><i><span style="font-family:Verdana;">G</span></i><span style="font-family:Verdana;">16800, and natural resistance-associated macrophage protein (</span><i><span style="font-family:Verdana;">NRAMP</span></i><span style="font-family:Verdana;">). Ni toxicity was assessed by treating seedlings with an aqueous solution of nickel nitrate salt [Ni(NO</span><sub><span style="font-family:Verdana;">3</span></sub><span style="font-family:Verdana;">)</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">] at the concentrations of 150 mg, 800 mg, and 1600 mg of nickel per 1 kg of dry soil. RT-qPCR was used to measure the expression of </span><i><span style="font-family:Verdana;">AT</span></i><span style="font-family:Verdana;">2</span><i><span style="font-family:Verdana;">G</span></i><span style="font-family:Verdana;">16800, and </span><i><span style="font-family:Verdana;">NRAMP</span></i><span style="font-family:Verdana;"> genes in samples treated with nickel nitrates and controls. The results revealed that </span><i><span style="font-family:Verdana;">P.</span></i> </span><i><span style="font-family:Verdana;">glauca</span></i><span style="font-family:""><span style="font-family:Verdana;"> is resistant to Ni based on lack of plant damage at all nickel concentrations. Ni has no effect on the expression of the </span><i><span style="font-family:Verdana;">AT</span></i><span style="font-family:Verdana;">2</span><i><span style="font-family:Ver
